Field of the Invention
The present invention relates to a machine tool capable of performing complex machining, or performing not only turning but also some work of a machining center.
Background of the Invention
A complex-machining machine tool capable of performing various kinds of machining such as turning and some work of a machining center has been recently developed as disclosed in the Japanese Patent Applications (OPI) No. 227343/84, No. 227345/84 and No. 56840/85 (the term "OPI" as used herein means an "unexamined published application").
In such a complex-machining machine tool disclosed in the Japanese Patent Application (OPI) No. 227343/84, a headstock is secured to a bed, and a saddle rotatably supporting a tool post is supported on the bed so that the saddle can be moved in the direction of a Z-axis coincident with the axis of a spindle and can also be moved in the direction of an X-axis perpendicular to the Z-axis. The axis of rotation of the tool post crosses the Z-axis at an angle of 45.degree.. A turning tool and a rotary tool are attached to the tool post so that the tools extend perpendicularly to each other. The tool post is moved in the directions of the Z-axis and the X-axis to perform prescribed machining on a workpiece held on the spindle. At that time, the tool post can be rotated by an angle of 180.degree. to machine both the front and side of the workpiece by the single rotary tool or turning tool.
In a complex-machining machine tool disclosed in the Japanese Patent Application (OPI) No. 227345/84 and capable of performing the same machining as that disclosed in the Japanese Patent Application (OPI) No. 22343/84, a tool magazine is provided so that it can be moved in the direction of a Z-axis (coincident with the axis of a spindle) synchronously with a saddle supporting a tool post. To change a tool, the saddle is moved only in the direction of an X-axis.
In a complex-machining machine tool disclosed in the Japanese Patent Application (OPI) No. 56840/85, a headstock is secured on a bed, and a turret-type tool post is provided on the bed so that the tool post can be moved in the direction of a Z-axis coincident with the axis of a spindle and be moved in the direction of an X-axis perpendicular to the Z-axis. A rotary tool and a turning tool are attached in symmetric positions to the tool post. A tool magazine is provided at one end of the bed. A first tool changer is provided at the tool magazine. A second tool changer is provided at the tool post. A changing carrier is provided between the first and the second tool changers. As result, tools can be changed for each other without much moving the tool post in the direction of the Z-axis.
However, the above-described conventional complex-machining machine tools have problems such as described below. Since the tool post of each of the machine tools is moved only in the directions of the X-axis and the Z-axis, special machining such as oblique boring and boring off the axis of the spindle cannot be performed although simple machining can be performed on the front and side of a workpiece. Particularly, although complex-machining machine tools (turning centers) have been recently built as flexible machining systems desired to be capable of performing various kinds of machining, the above-described conventional machine tools cannot meet the desire.
Since each of the conventional complex-machining machine tools have the tool magazine usually at the end of the bed in the direction of the Z-axis, the tool post needs to be moved in the direction from a turning position to the tool magazine at the end of the bed in order to change tools for each other. For that reason, it is time-consuming to exchange the tools for each other. The length of the movement of the tool post in the direction of the Z-axis is elongated according to the complexmachining machine tool becoming large, so that it is more time-consuming to move the tool post in the direction of the Z-axis and to exchange the tools.
In the complex-machining machine tool disclosed in the Japanese Patent Application (OPI) No. 227345/84, the tool magazine can be moved in order to quickly change the tools for each other. For such purpose, however, a mechanism for moving the tool magazine of large weight is needed. Besides, it is dangerous to move the tool magazine fitted with tools.
In the complex-machining machine tool disclosed in the Japanese Patent application (OPI) No. 56840/85, the two tool changers are provided in order to shorten the time of the tool changing. However, since the two tool changers are provided and the changing carrier is needed, the tooling space is reduced due to the presence of the tool changers and the changing carrier and the machine tool is enlarged.